The present invention relates a rain sensor system for a motor vehicle having a sensor element for detecting moisture on its surface and having an evaluation electronics connected with the sensor element by which, above a certain limit value of the moisture, a windshield wiper which wipes a window of the motor vehicle and the sensor element can be controlled.
Such rain sensors are used in modern motor vehicles and are thus known. In order to determine the degree of wetness, sensor elements are used which, for instance, change their ohmic resistance or their capacitance as a function of the degree of wetness present on their surface. Generally the sensor element consists of conductive paths applied to the windshield of the vehicle in the region of the windshield wiper. As a function of the degree of wetness the sensor element gives off an electric signal to the evaluation electronics located within the motor vehicle. Above a given limit value of the signal, the evaluation electronics activates the windshield wiper. Such rain sensors are used on windshields and rear windows of motor vehicles.
The known rain sensor has the disadvantage that the sensor element must be constructed by being integrated in or on the glass of the windshield or window. This results in a cost-intensive manufacture of the rain sensor together with the windshield and/or a high expense for the logistics. Furthermore, there is the disadvantage that an equipping of an existing motor vehicle, subsequent to its manufacture, with the known rain sensor is very expensive.